Free and conjugated phenolic compounds and their antioxidant activities in regular and non-darkening cranberry bean (Phaseolus vulgaris L.) seed coats
Citation
Chen, P.X., Bozzo, G.G., Freixas-Coutin, J.A., Marcone, M.F., Pauls, P.K., Tang, Y., Zhang, B., Liu, R., Tsao, R. (2015). Free and conjugated phenolic compounds and their antioxidant activities in regular and non-darkening cranberry bean (Phaseolus vulgaris L.) seed coats. Journal of Functional Foods, [online] 18 1047-1056. http://dx.doi.org/10.1016/j.jff.2014.10.032
Abstract
Postharvest darkening in dry bean (Phaseolus vulgaris L.) negatively impacts consumer preference. Regular-darkening (RD) and non-darkening (ND) cranberry beans were profiled for seed coat phenolics using HPLC-DAD/LC-ESI-MS. n and assessed for antioxidant activity using oxygen radical absorbing capacity (ORAC) and ferric-reducing antioxidant power (FRAP) assays. Flavonoids were exclusive to free phenolic extracts of RD beans. Total phenolic content (TPC) was significantly higher (p < 0.05) in RD seed coats (52.41-56.43 mg GAE/g) compared to ND seed coats (2.00-2.06 mg GAE/g). Alkaline hydrolysis revealed the presence of phenolic acids and flavonoid conjugates in RD beans. Only p-coumaric and ferulic acids were found in ND beans. Overall antioxidant activity was stronger in RD seed coats (125.28-287.87 μmole TE/g and 20.71-54.01 μmole AAE/g) compared to ND seed coats (2.11-10.09 μmole TE/g and 0.73-1.88 μmole AAE/g). This is the first report of specific flavonoids in cranberry beans.